US Patent 7527043 Liquid fuel system with anti-drainback valve and engine using same

An engine with a high pressure common rail fuel system includes a bleed line to tank to facilitate evacuation of air and vapor from the fuel lines to assist in priming the fuel system. An anti-drainback valve prevents fuel vapor from migrating in a reverse direction through the bleed line toward the fuel pump during long periods of engine shut down. The inclusion of the anti-drainback valves helps facilitate short cranking times on the order of three seconds or less during engine start up, even after prolonged periods of engine shut down.